1. Field of the Invention
The present invention relates to a commutator for a dynamo-electric machine comprising equalizer segments electrically connecting commutator segments which are to have the same electric potential, and to a method of manufacturer therefor.
2. Description of the Related Art
FIG. 26 is a partial cross-section of an electric motor which is a conventional dynamo-electric machine. In the electric motor, a commutator assembly 2 is disposed in the vicinity of an armature 1.
The armature 1 comprises a core 3 having a plurality of slots extending longitudinally, and windings 4 composed of wire wound into the slots by a lap-winding method.
The commutator assembly 2 comprises a commutator 8 and brushes (not shown) contacting the surface of the commutator 8. The commutator 8 comprises a plurality of commutator segments 5 disposed around the circumference thereof having risers 6 electrically connected to the windings 4, an insulating resin portion 7 securing the commutator segments 5, and equalizers 9 electrically connecting commutator segments 5 which are to have the same electric potential. The equalizers 9 comprises a plurality of equalizer segments 11 like the one shown in FIG. 27, the tips 10 thereof being secured to the risers 6 by brazing or the like. The equalizer segments 11 are secured and supported by securing members 12, and the equalizer segments 11 are designed to be able to resist centrifugal force with the assistance of the securing members 12.
In the above 4-pole, lap-wound electric motor, by supplying electric current to the windings 4 from outside by means of the brushes contacting the commutator segments 5, the armature 1 and commutator 8 which are secured to a rotor shaft (not shown) rotate together with the rotor shaft due to electromagnetic effects.
In a commutator 8 for an electric motor of the above construction, the equalizers 9 are provided to prevent the generation of circulating currents running through the brushes due to differences in induced voltage between circuits of the windings 4, but one problem has been that these equalizers 9 require the securing members 12 for support, increasing the number of parts.
A further problem has been that the equalizers 9 have been disposed separately from the commutator segments 5, necessitating the procuration of space for the equalizers 9, making the size of the commutator assembly that much larger.